1. Field of the Invention
The present invention relates to an automatic blade changing system which automatically changes blades in a dicing machine which dices a semiconductor wafer, etc.
2. Description of Related Art
The dicing machine dices the semiconductor wafer by rotating, at high speed, a thin blade which is made of abrasive grains such as diamond strengthened by nickel, etc. FIG. 1 shows an example of a conventional blade attachment structure in the dicing machine. As shown in FIG. 1, a support 13, an engaging part 14, a thread 15, and a hexagon hole 16 for fixing a spindle 11 are provided at the end of the spindle 11. A blade 17 is fixed to a hub member 18, which is provided with an engaging part 19 which is engaged with the engaging part 14. The blade 17 is pressed in order to come into contact with the support 13 so that the engaging part 14 can be engaged with the engaging part 19. A thread 21 of a nut 20 is engaged with the thread 15. The blade 17 requires the good rotational balance to rotate at ultrahigh speed. The rotational balance of the blade 17 is adjusted in advance with respect to a rotary shaft which is engaged with the engaging part 19, and therefore, the good rotational balance can be obtained by engaging the engaging parts 14 and 19.
The blade becomes worn as cutting proceeds, and it is necessary to replace the blade which has become worn to a predetermined limit. Moreover, blades must be changed in accordance with a change in cutting shapes. Thus, it is necessary to change blades frequently in the dicing machine. To change blades, a hexagon wrench is inserted into a hexagon hole 16 to prevent the rotation of the spindle 11, and the nut 20 is turned and removed. On removal of the hexagon wrench, the nut 20 and the blade 17 are removed. Then, another blade and the nut 20 are attached. The hexagon wrench is inserted into the hexagon hole 16 to prevent the rotation of the spindle, and the nut 20 is turned, threaded into the spindle and fixed. Since it is difficult to automatically change blades, the replacement is currently performed manually.
As part of the labor saving scheme for the dicing machine, workpieces are supplied and collected automatically, and the cutting parts thereof are recognized automatically. The automation is particularly important in the process of manufacturing the semiconductor apparatus since an operator has to supervise a number of dicing machines. As stated above, the manually-performed blade replacement is an obstacle to automation of the dicing operation as a whole.
To solve the above-mentioned problem, Japanese Utility Model Provisional Publication No. 5-59846 and Japanese Patent Provisional Publication No. 6-326186 disclose an automatic blade changer which has a blade attachment and detachment means and a nut attachment and detachment means. They also disclose a blade attachment and detachment means which attaches and detaches an old blade attached to the spindle, and another blade attachment and detachment means which attaches and detaches a new blade which is to be attached to the spindle. Japanese Utility Model Provisional Publication No. 7-17443 discloses an automatic blade changer which is provided with an engagement easing means for heating the blade to facilitate the attachment and detachment thereof. The above-mentioned automatic blade changers, however, have a problem in that the structure is very complex, requires high costs, and the replacement is also complicated, since both of the blade attachment and detachment means and the nut attachment and detachment means have to be provided. Japanese Utility Model Provisional Publication No. 5-59846 and Japanese Patent Provisional Publication No. 6-326186 also disclose the structure in which the blade attachment and detachment means is integrated with the nut attachment and detachment means, but the structure is very complex due to the necessity of providing the two means.
To solve the above-mentioned problems, the applicant of the present invention disclosed in Japanese Patent Provisional Publication No. 6-262515 a blade which is integrated with a thread for attachment. The use of such a blade eliminates the necessity for removing and holding the nut, thus, simplifying the structure of the automatic blade changing system.
The blade of Japanese Patent Provisional Publication o. 6-262515 is completely different from blades which are commonly used. Currently, the standardized blades with equal shape are commonly used for the dicing machine. For this reason, it has been desired to provide, at lower cost, an automatic blade changing system which is able to change blades which are commonly used.